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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/96793] __builtin_floor produces wrong result when rounding direction is FE_DOWNWARD
Date: Wed, 23 Dec 2020 08:20:23 +0000 [thread overview]
Message-ID: <bug-96793-4-xzJYg0S4G4@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-96793-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96793
--- Comment #21 from Uroš Bizjak <ubizjak at gmail dot com> ---
https://gcc.gnu.org/g:c40b640ebcef1aae78eaca56e04d204dda9e4cad
commit r9-9126-gc40b640ebcef1aae78eaca56e04d204dda9e4cad
Author: Uros Bizjak <ubizjak@gmail.com>
Date: Wed Dec 23 09:09:29 2020 +0100
i386: Fix __builtin_floor with FE_DOWNWARD rounding direction [PR96793]
x86_expand_floorceil expander uses x86_sse_copysign_to_positive, which
is unable to change the sign from - to +. When FE_DOWNWARD rounding
direction is in effect, the expanded sequence that involves subtraction
can trigger x - x = -0.0 special rule. x86_sse_copysign_to_positive
fails to change the sign of the intermediate value, assumed to always
be positive, back to positive.
The patch adds one extra fabs that strips the sign from the intermediate
value when flag_rounding_math is in effect.
2020-12-22 Uroš Bizjak <ubizjak@gmail.com>
gcc/
PR target/96793
* config/i386/i386.c (ix86_expand_floorceil):
Remove the sign of the intermediate value for flag_rounding_math.
(ix86_expand_floorceildf_32): Ditto.
gcc/testsuite/
PR target/96793
* gcc.target/i386/pr96793.c: New test.
next prev parent reply other threads:[~2020-12-23 8:20 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-26 9:10 [Bug c/96793] New: " chfast at gmail dot com
2020-08-26 9:11 ` [Bug c/96793] " chfast at gmail dot com
2020-08-26 9:11 ` chfast at gmail dot com
2020-08-26 9:12 ` chfast at gmail dot com
2020-08-26 9:21 ` chfast at gmail dot com
2020-08-26 10:46 ` [Bug target/96793] " rguenth at gcc dot gnu.org
2020-08-26 11:17 ` ubizjak at gmail dot com
2020-08-28 7:26 ` ubizjak at gmail dot com
2020-08-28 7:26 ` ubizjak at gmail dot com
2020-08-28 8:58 ` chfast at gmail dot com
2020-08-28 9:00 ` ubizjak at gmail dot com
2020-08-28 9:40 ` rguenth at gcc dot gnu.org
2020-08-28 9:48 ` ubizjak at gmail dot com
2020-08-28 9:54 ` ubizjak at gmail dot com
2020-08-28 11:31 ` glisse at gcc dot gnu.org
2020-08-28 12:20 ` glisse at gcc dot gnu.org
2020-08-28 14:06 ` chfast at gmail dot com
2020-08-28 14:31 ` chfast at gmail dot com
2020-08-28 14:37 ` ubizjak at gmail dot com
2020-12-22 12:17 ` ubizjak at gmail dot com
2020-12-22 17:20 ` ubizjak at gmail dot com
2020-12-22 20:13 ` ubizjak at gmail dot com
2020-12-23 8:20 ` ubizjak at gmail dot com [this message]
2020-12-23 8:21 ` ubizjak at gmail dot com
2020-12-23 8:21 ` ubizjak at gmail dot com
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